This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2000-360062, filed Nov. 27, 2000, the entire contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to a detector unit incorporated in an X-ray computer tomographic photographing device (hereinafter referred to as xe2x80x9cX-ray CT devicexe2x80x9d), an X-ray CT device, an X-ray detector and an X-ray detector manufacturing method. More particularly, it relates to a device capable of positioning the detector unit at a desired place with respect to a collimator for removing scattered X rays.
2. Description of the Related Art
With request for higher resolution and definition of an X-ray CT image, the use of a multislicing type X-ray CT device has become frequent, and it has been put to practical use. In this X-ray CT device, the scintillator block of a solid-state detector has a two-dimensional sequence structure similar to the pattern of a photodiode. As a result, it is necessary to increase positioning accuracy concerning the arrangement of individual scintillator segments, thereby to render X rays visible in each of a plurality of detector units arrayed in a circular-arc collimator.
The adjustment of such a detector in a channel direction (i.e. the circumferential direction of the collimator) necessitates positioning such that pitches can match one another for a collimator single plate. In addition, in the above-described multislicing type X-ray CT device, highly accurate adjustments may be required not only in a channel direction but also in a slicing direction (i.e., the height direction of the collimator).
On the other hand, as a technology for obtaining an image in real time, the use of a large-area detector has been studied. However, in a currently mainstream solid-state detector, it is practically difficult to achieve a large area for a photodiode chip because of constraints imposed on a wafer size, material yield, workability, and a manufacturing device. In addition, with regard to a scintillator material, it is difficult to directly manufacture a large-area detector because of constraints imposed on an ingot size, material yield, workability, and so on.
The following problem has been discovered in the foregoing conventional multislicing type X-ray CT device. Specifically, when the detector unit is positioned with respect to the collimator, an adjustment device must be provided to perform highly accurate positioning. Thus, even when an abnormality occurs in the detector unit of a shipped X-ray CT device, and the necessity of replacing the detector unit is determined, a special device must be provided to perform highly accurate positioning, making it impossible to replace the detector unit on the spot. Consequently, the entire X-ray detector was removed from the X-ray CT device, and replaced by another.
On the other hand, in the X-ray CT device using the foregoing large-area detector, since the collimator was similarly enlarged, the warping of the collimator single plate was difficult.
Therefore, objects of the present invention are to provide a detector unit capable of easily positioning a detector with respect to a collimator without needing any special devices, and only by mechanical assembling without being conscious of any adjustments, an X-ray CT device, and a device and a method for positioning the detector unit.
In order to achieve the foregoing object, in accordance with the invention, there is provided a detector unit for detecting X rays passed through a collimator having a plurality of collimator single plates. This detector unit comprises: a substrate attached to a collimator support for supporting the collimator; a photodetecting device array including photodetecting devices mounted on the substrate; a scintillator block arranged corresponding to the photodetecting device array, and provided on the photodetecting device array to convert the X rays into light; and an engaging component having an engaging portion provided on the collimator single plate side of the substrate, and engaged with the collimator single plate to regulate a position of the photodetecting device array or the scintillator block in a channel direction with respect to the collimator single plate.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.